Machine-translated by Google. Questions are authored in English.
Top

Discussion

The remainder when the positive integer m is divided by 7 is x. The remainder when m is divided by 14 is x+7.

Which one of the following could m equal?

  • A.45
  • B.53
  • C.72
  • D.85

Answer: B

Test each candidate against both conditions, since the second is far more restrictive than it looks:

mm mod 7 = xm mod 14x + 7fits?
453310no
5341111yes
72229no
85118no

The pattern behind it: dividing by 14 leaves either \( x \) or \( x+7 \), and the second happens exactly when the quotient by 7 is odd. Here \( 53 = 7 \times 7 + 4 \), and that quotient 7 is odd, so the remainder on 14 is \( 4 + 7 = 11 \).

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.